Research Project: Management of Filth Flies

Location: Mosquito and Fly Research

2019 Annual Report

Objectives
1. Evaluate the effects of climate change on filth fly populations and their natural enemies. 1A. House fly management under high temperature conditions. 1B. Verify seasonality, resource preference and range of Stomoxys niger in East Africa. 2. Increase the efficiency of integrated pest management programs by the development and improvement of traps and behavior-altering surfaces and chemicals. 2A. Identify and develop stable fly optical or chemical attractants which will improve trap efficacy. 2B. Conceive of or develop applications for behavior-altering devices, surfaces and chemicals (e.g., attractants, repellents, and pesticides) for practical use on and around livestock and poultry. 3. Develop management techniques for fly larvae. 3A. Development of more effective larval detection and control techniques for filth flies. 3B. Autodissemination of Insect Growth Regulators (IGR’s) by house flies. 4. Improve biological control techniques for filth flies. 4A. Improved efficacy of Beauveria bassiana by formulating combination products with other agents. 4B. Location of host pupae by filth fly parasitoids. 4C. Improve the quality of commercially available fly parasitoids.

Approach
Objective 1 will investigate and identify methods for management of house flies under the higher temperatures expected to occur with global warming. It will also use trapping data to determine risk of introduction of exotic Stomoxys spp. in the U.S. Objective 2 will develop chemical or optical attractants that will enable traps for stable flies to become more efficient and capture greater numbers of flies. It will also adapt behavior-altering devices, such as pesticide-impregnated fabrics, for different uses, such as attract and kill devices. Objective 3 will evaluate new methods for determining the presence of sub-surface immature fly populations in field habitats. It will also further develop methods to allow house flies to spread selected IGRs throughout their habitats. Objective 4 will improve the efficacy of a biological control agent by formulating it with other selected lethal agents. It will also investigate the methods (e.g., chemical cues) used by parasitic wasps to locate fly pupae in field habitats. Finally, we will gain new knowledge on the effects of long-term colonization on the performance of parasitic wasps being released into the field.

Progress Report
This is the final report for project 6036-32000-049-00D. Data from the previous years’ research on the effects of high temperatures on flies and parasitoids were analyzed and two papers were submitted for publication in the Journal of Medical Entomology. Both papers were accepted for publication in May-June 2019. Work on optically attractive cloth targets was completed sooner than expected and a paper has been published. Reducing target size was the key to making the targets easier to use and easier to transport. Attempts to interest industry partners have so far been unsuccessful. Devices to physically capture flies without adhesives were evaluated but were found to be ineffective because more testing was required to determine the optimum size for the openings in the cloth substrate that would entangle the feet of the flies. Work has been delayed because a major cooperator has been assigned to another job position. Tests with the attract and kill device are or will be conducted in the field during the 2019 fly season in the U.S., Costa Rica and Greece. Flies are attracted to this device by a commercial trap, but they must pass through holes in a pesticide-treated fabric surrounding the trap to reach the attractive trap surface. Hole size impedes passage through the treated fabric long enough for the fly to acquire a toxic dose of pesticide. Capture of headspace volatiles produced by fly larvae developing in selected laboratory media or substrates continues at a very slow pace because the key cooperator no longer works full time at our laboratory. Efforts are being made to find a new cooperator who will be willing to continue the work. This subobjective was re-directed towards determining the practicality of releasing pyripoxyfen-treated flies instead of using autodissemination stations. The proportion of treated flies in a population needed to provide satisfactory control was determined. This study and the autodissemination work from previous years were submitted to and published in the Journal of Pest Science. Work on combining Beauveria bassiana with bacterial pathogens for adult fly control was completed in 2018. Work continued on evaluating efficacy of B. bassiana against fly larvae. House fly larvae are exceptionally difficult to infect with B. bassiana, probably because their constant movement through a wet substrate prevents spore attachment and germination. A strain of B. bassiana isolated from Florida house flies (strain NFH10) was subjected to selection over 10 generations to produce a strain with a faster kill rate. Parasitoid responses to extracts of hosts and host media were weak, and there was no measurable attraction to different fractions of those extracts.

Accomplishments
1. Artificial sweeteners offer an alternative tool for fly control. Although their mode of action is not known, the artificial sweeteners xylitol and erythritol are toxic to several species of adult flies. In this study, an ARS researcher in Gainesville, Florida, and a colleague at Northern Illinois University evaluated the effect of these sweeteners on larvae of house flies and stable flies. Larvae of both species were more sensitive to erythritol than xylitol, and stable flies were more sensitive than house flies. Adult flies could not distinguish between untreated larval media and media treated with the sweeteners, and they readily laid eggs on both types. These sweeteners appear to have potential as an inexpensive way to control flies without using conventional insecticides.

2. Stable fly trap becomes an attract and kill device. Effective stable fly traps are sold commercially, but these traps require regular servicing to keep catching flies. This means maintaining service personnel and supplies needed to service the traps. An ARS researcher in Gainesville, Florida, selected a trap, surrounded it with a light frame and pesticide-treated fabric to determine how these items affected trap attraction. Holes were cut in the fabric to increase visual attraction. Flies attracted to the trap squeezed through the holes and died from increased exposure to the pesticide in the fabric. These devices will greatly reduce the number of trap service personnel and the time and supplies required. This will result in a significant savings for producers who use large-scale trapping systems as part of their stable fly management program.

3. House fly susceptibility to low-cost essential oils. House flies are resistant to every known fly control insecticide, so new fly control tools are a critical need. Essential oils of vetiver, cinnamon, lavender and sunflower were evaluated for insecticidal and repellent properties by an ARS researcher in Gainesville, Florida, and an Egyptian colleague. All oils caused 94-100% mortality of fly larvae and killed 100% of exposed adults. Vetiver and cinnamon oils repelled 84 and 78% of larvae, respectively, but not adult flies. Adults were repelled by neem oil and p-methane-3,8-diol (PMD). Based on efficacy and cost, cinnamon oil has the most potential for further development. It is classified by EPA as sufficiently safe, which precludes registration as a pesticide. Thus, new products containing this oil could be developed easily and with few regulatory challenges.

4. High temperatures give house flies an advantage over their natural enemies. House flies are a difficult to control but important pest of humans and animals. Fly control is conducted under hotter conditions because of climate changes. But most management strategies were designed for regions with moderate temperatures. Hot temperatures could affect the balance between the fly and wasp parasites that kill the fly in the pupal stage. An ARS researcher in Gainesville, Florida, and Israeli colleagues compared the heat tolerance of fly and wasp populations in the U.S. Only one wasp species, Muscidifurax zaraptor, was as heat-tolerant as the flies. Results show that M. zaraptor is the most effective wasp parasitite for fly control under hot conditions. More heat-tolerant wasp populations might be discovered with further exploration.

Review Publications
Hogsette, Jr, J.A. 2019. Turning ultraviolet light traps on and off increases their attraction to house flies (Diptera: Muscidae). Journal of Insect Science. 19(1):1-3. https://doi.org/10.1093/jisesa/iey126.
Machtinger, E.T., Geden, C.J. 2018. Biological control with parasitoids. In: Garros, C., Bouyer, J., Takken, W. and Smallegange, R.C. editors. Pests and Vector-Borne Diseases in the Livestock Industry. Wageningen, The Netherlands: Wageningen Academic Publishers. 5:611. https://doi.org/10.3920/978-90-8686-863-6_11.
Weeks, E.N., Machtinger, E.T., Leemon, D., Geden, C.J. 2018. Biological control of livestock pests: entomopathogens. In: Garros, C., Bouyer, J., Takken, W. and Smallegange, R.C. editors. Pests and Vector-Borne Diseases in the Livestock Industry. Wageningen, The Netherlands: Wageningen Academic Publishers. 5:337-387. https://doi.org/10.3920/978-90-8686-863-6_12.
Biale, H., Chiel, E., Geden, C.J. 2019. Autodissemination of pyriproxifen as a method for controlling the house fly Musca domestica. Journal of Pest Science. 92(3):1283-1292. https://doi.org/10.1007/s10340-019-01092-x.
Sanscrainte, N.D., Waits, C.M., Geden, C.J., Estep, A.S., Becnel, J.J. 2018. Reproducible dsRNA microinjection and oviposition bioassay in mosquitoes and house flies. Journal of Visualized Experiments. (141):e58650. https://doi.org/10.3791/58650.
Khater, H., Geden, C.J. 2018. Potential of essential oils to prevent fly strike and their effects on the longevity of adult Lucilia sericata. Journal of Vector Ecology. 43(2):261-270. https://doi.org/10.1111/jvec.12310.
Burgess, E.R., Geden, C.J. 2019. Larvicidal potential of the polyol sweeteners erythritol and xylitol in two filth fly species. Medical and Veterinary Entomology. 44(1):11-17. https://doi.org/10.1111/jvec.12324.
Johnson, D.M., Weeks, E.N., Lovullo, E.D., Shirk, P.D., Geden, C.J. 2018. Mortality effects of three bacterial pathogens and Beauveria bassiana when topically applied or injected into house flies (Diptera: Muscidae). Journal of Medical Entomology. 56(3):774-783. https://doi.org/10.1093/jme/tjy218.
Tam, T.L., Hogsette, Jr, J.A., Tenbroeck, S.H. 2019. Can attractive sticky traps be used to protect horses from the bites of Stomoxys calcitrans (L.) (Diptera: Muscidae). Journal of Economic Entomology. https://doi.org/10.1093/jee/toz134.
Geden, C.J., Biale, H., Chiel, E., Johnson, D.M. 2019. Effect of fluctuating high temperatures on house flies (Diptera: Muscidae) and their principal parasitoids (Muscidifurax spp. and Spalangia spp. [Hymenoptera: Pteromalidae]) from the United States. Journal of Medical Entomology. https://doi.org/10.1093/jme/tjz080.